Is there a way to group or organise keyframes for a complex animation?
Short answer: Dope Sheet and NLA editor
Dope sheet shows you all keyframes categorized in objects, then axes or properties. You have a complete overview and you can set it up to either show all keyframes in the scene or just of the selected object (click on the little arrow on the navigation bar in the dope sheet window).
For detailed edits you might also want to use the graph editor, which isn't good for an organized overview but let's you edit the key curves in Detail.
The NLA editor can store &quot;animation templates&quot;. So for example you can create an idle animation for a character and a running animation and save both as &quot;actions&quot; in the NLA editor. It's layer based and you can do tons of stuff there to make complicated animations easy to manage. You could for example loop an action or layer multiple on top of each other (idle + running for example).